Commit e9635f2a authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'x86_fred_for_v7.1_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 

Pull x86 FRED updates from Borislav Petkov:
 "We made the FRED support an opt-in initially out of fear of it
  breaking machines left and right in the case of a hw bug in the first
  generation of machines supporting it.

  Now that that the FRED code has seen a lot of hammering, flip the
  logic to be opt-out as is the usual case with new hw features"

* tag 'x86_fred_for_v7.1_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/fred: Remove kernel log message when initializing exceptions
  x86/fred: Enable FRED by default
parents fabd5a8d f0958d58

Documentation/admin-guide/kernel-parameters.txt

+2 −2
Original line number Diff line number Diff line
@@ -1765,8 +1765,8 @@ Kernel parameters 
	fred=		[X86-64]

			Enable/disable Flexible Return and Event Delivery.

			Format: { on | off }

			on: enable FRED when it's present.

			off: disable FRED, the default setting.

			on: enable FRED when it's present, the default setting.

			off: disable FRED.



	ftrace=[tracer]

			[FTRACE] will set and start the specified tracer

arch/x86/Kconfig

+1 −1
Original line number Diff line number Diff line
@@ -554,7 +554,7 @@ config X86_FRED 
	bool "Flexible Return and Event Delivery"

	depends on X86_64

	help

	  When enabled, try to use Flexible Return and Event Delivery

	  When enabled, use Flexible Return and Event Delivery

	  instead of the legacy SYSCALL/SYSENTER/IDT architecture for

	  ring transitions and exception/interrupt handling if the

	  system supports it.

arch/x86/kernel/cpu/common.c

+1 −1
Original line number Diff line number Diff line
@@ -1761,7 +1761,7 @@ static void __init cpu_parse_early_param(void) 


	/* Minimize the gap between FRED is available and available but disabled. */

	arglen = cmdline_find_option(boot_command_line, "fred", arg, sizeof(arg));

	if (arglen != 2 || strncmp(arg, "on", 2))

	if (arglen == 3 && !strncmp(arg, "off", 3))

		setup_clear_cpu_cap(X86_FEATURE_FRED);



	arglen = cmdline_find_option(boot_command_line, "clearcpuid", arg, sizeof(arg));

arch/x86/kernel/fred.c

+0 −3
Original line number Diff line number Diff line
@@ -27,9 +27,6 @@ EXPORT_PER_CPU_SYMBOL(fred_rsp0); 


void cpu_init_fred_exceptions(void)

{

	/* When FRED is enabled by default, remove this log message */

	pr_info("Initialize FRED on CPU%d\n", smp_processor_id());



	/*

	 * If a kernel event is delivered before a CPU goes to user level for

	 * the first time, its SS is NULL thus NULL is pushed into the SS field